Maybe I'm reading into the Akuzawa clip---easy to do since you can't hear what he's saying---but he shakes his head, so it seems like a negative example. Maybe Rob can jump in and explain what was going on in the clip. But here's what I think he's doing:

1) He's getting under uke's attack (as Mike said).
2) He's bringing his elbows together. This aligns his forearms with his body, which is a pretty strong position. It also has the added benefit of twisting uke's arms out of alignment.
3) Lastly, with his arms "locked" in place, he's using his legs to lift up uke.

This was the way I was taught to execute kokyo-ho. It works. With a little practice, you can lift uke's arms "without any effort" from your upper body.

But it's not internal movement. When Akuzawa does it the second time, you don't see him doing any of the above. He "simply" raises his arms.